Project Summary/Abstract ?TR&D 3 User demand for CFT is extremely high. This is to be expected, given most cell biologists with a need for SXT imaging also have a ready-made supply of labeled cells suitable for fluorescence imaging, and therefore suitable for correlated CFT-SXT. In this TR&D we will replace our proof of concept cryo-light microscope with a more robust, higher resolution instrument. We will also develop a user-friendly software package for cryo- fluorescence tomography data collection on this microscope. The data collection software will link seamlessly to a new unified data analysis package. As a result, Users will be able to collect and process data using a single, familiar looking GUI. Finally, we will also characterize the low-temperature behavior of a fluorescent labels, and explore new opportunities in cryogenic microscopy, such as stochastic localization imaging.